public string Add(RomanNumber rhs)
{
var thisInt = this.ToInt();
var otherInt = rhs.ToInt();
int result = thisInt + otherInt;
string resStr = "";
resStr += this.AddDivisor(10, 'X', ref result);
resStr += this.AddDivisor(5, 'V', ref result);
resStr += this.AddDivisor(1, 'I', ref result);
resStr = resStr.Replace("IIII", "IV");
return resStr;
}
public void ConvertsToIntegerCorrectly(string roman, int expectedInt)
{
var romanNumber = new RomanNumber(roman);
Assert.AreEqual(expectedInt, romanNumber.ToInt());
}